It is demanded that a multilayer ceramic capacitor is downsized and a capacity of the multilayer ceramic capacitor is enlarged. There are methods for enlarging the capacity without enlarging a size as follows. (1) A relative dielectric constant of a dielectric material is enlarged. (2) A thickness of dielectric layers is reduced. (3) The number of the dielectric layers is enlarged. (4) An area of effective intersection of a dielectric region (an area in which an internal electrode connected to an external electrode faces with another internal electrode connected to another external electrode) is enlarged. With the methods, it is possible to enlarge a capacity of a multilayer ceramic capacitor of which a rated voltage is small.
As an example, the multilayer ceramic capacitors are used as smoothing circuits. In the smoothing circuits, DC bias characteristic is important. This is because an effective capacity may decrease because of a DC component in a capacitor using a ferroelectric material (for example, see Japanese Patent Application Publication No. 2004-323315). When the effective capacity decreases, the capacitor is not effective for smoothing.
When a dielectric constant of a dielectric material is increased in accordance with the method (1), the bias characteristic is degraded. Therefore, the method (1) is not preferable in a capacitor used for smoothing. When the thickness of the dielectric layers is reduced in accordance with the method (2), electric field intensity applied between internal electrode layers increases and the bias characteristic is degraded. Therefore, the method (2) is not preferable. In the method (3), when the number of stacking is increased, a multilayer ceramic capacitor gets higher and a size of the capacitor is enlarged. Therefore, the method (4) is the most effective with respect to a multilayer ceramic capacitor in which enlargement of capacity (specifically effective capacity) is demanded without enlarging the size.
As a concrete method for enlarging the effective intersection area, slurry for forming a side margin region is coated, after stacking green sheets (for example, see Japanese Patent Application Publication No. H03-108306).